1. Field of the Invention
The present invention relates to a work conveying system and a traveling path sealing structure in the work conveying system. Particularly, the present invention is concerned with an improvement of a work conveying system and a traveling path sealing structure wherein, in a production line installed within a clean room for the production of, for example, semiconductor components, liquid crystal display panels, medical supplies, drugs, or processed foods, dust generated in the interior of a traveling path (guide rail) in the work conveying system is prevented from leaking out into the clean room, the work conveying system being adapted to convey a work to each of plural processing apparatuses while allowing the work to circulate among the processing apparatuses.
2. Description of the Prior Art
In a semiconductor integrated circuit or a liquid crystal display panel, the deposition of dust causes a lowering of product yield. As to medical supplies, drugs and processed foods, it is desirable for them to be produced in a sterile and sanitary environment. In this connection, intra-clean room production lines are in operation in a wide variety of fields including those production fields, and various technical developments have been made with respect to various processing chambers and work conveying systems installed within clean rooms.
As to the work conveying system, an overhead traveling type work conveying system has been developed. According to this work conveying system, a layout mode of various processing apparatuses to be installed within a clean room is difficult to be restricted and it is possible to select an optimum layout, that is, it is possible to utilize the interior of the clean room effectively and thereby possible to reduce the equipment cost and operation cost of the clean room. The adoption of such an optimal layout is advantageous also in that the work conveying system which can be a generation source of dust (particles) can be kept away from apparatuses such as various processing chambers installed within the clean room.
The applicant in the present case has previously invented a work conveying system provided with moving means capable of moving a work holding means in arbitrary three-dimensional directions in the upper ceiling space within the clean room and applied for a patent (see Japanese Patent Laid Open No. 2000-243808).
In this work conveying system, a pair of horizontal fixed guide rails are laid in parallel within a ceiling space and one or plural horizontal traveling guide rails are laid between the pair of fixed guide rails so that they can travel along the fixed guide rails. On each traveling guide rail is provided a traveling block which can travel along the traveling guide rail. A horizontal moving means is constituted by the fixed guide rails, traveling guide rail(s), and a traveling block. Further, the traveling block is provided with a vertical moving means which can move the work holding means up and down. A three-dimensional moving means is constituted by the horizontal moving means and the vertical moving means.
The fixed and traveling guide rails, which are each in an elongated duct shape, contain a drive portion (including a drive motor and a drive mechanism) for the traveling guide rail and the traveling block, also contain a power supply means, and are communicated with each other. Dust (particles) generated from the drive portion and various slide portions is confined into ducts which constitute the fixed and traveling guide rails and is sucked in from one end of a communication path and is discharged to the exterior of the clean room. In this way contamination in the clean room caused by dust present within the ducts which constitute the guide rails is prevented to a considerable extent.
However, the communication path which provides communication between the fixed guide rails and the traveling guide rail(s) is long and, while the dust present within the ducts as communication constituents of the guide rails is sucked in from one end of the communication path and is discharged to the exterior of the clean room, there is a fear that the dust may leak to a lower portion of the clean room from a gap in the communication path, especially from an elongated gap in which a connecting member for connection between the traveling guide rail(s) and the drive portion thereof extends through the duct as a constituent of a fixed guide rail or from an elongated gap in which a connecting member for connection between the traveling block and the drive portion thereof extends through the duct as a constituent of the traveling guide rail, with a consequent likelihood of lowering in the degree of cleanness of the clean room.
In FIG. 17 there is illustrated a sealing structure in this work conveying system, in which an elongated gap 028 formed in a portion where a connecting member 022 for connection between a traveling guide rail 015 and a drive portion thereof (including a drive motor 023 and a drive roller 026) extends through a duct 017 as a constituent of a fixed guide rail 014 is sealed. In this sealing structure, the connecting member 022 has a zigzag-bent sectional shape and shield plates 041a and 041b are inserted deep into slit portions (slits 022a and 022b) of the connecting member 022, thereby constituting a labyrinth to prevent dust generated in the drive and slide portions in the duct from leaking out into the clean room. However, even with such a labyrinth structure, since the suction of dust is performed through a long communication path, it has so far been impossible to completely prevent the dust present in the duct from leaking out to the lower portion of the clean room.
Other examples of overhead traveling type work conveying systems are disclosed in Japanese Patent Laid Open Nos. 1993-116885, 1993-39030, and 1995-291123. In these work conveying systems, a traveling roller provided in a traveling body is adapted to roll on a rail laid on a ceiling, whereby the traveling body travels. But a drive portion to drive the traveling roller is covered with a cover member attached to the traveling body itself, so that dust generated in the drive portion and a slide portion between the traveling roller and the rail is easy to be released into the clean room. Since the above conventional techniques are not dedicated to a clean room, they are not applicable to a satisfactory extent to a clean room for which a high degree of cleanness is required.
It is an object of the present invention to solve the above-mentioned problems involved in the conventional overhead traveling type work conveying system and provide a work conveying system and a traveling path sealing structure in the work conveying system which can prevent dust generated from a drive portion(s) and various slide portions in a traveling path of the work conveying system from leaking out into a clean room, the work conveying system comprising fixed guide rails and a traveling guide rail(s), and thereby prevent a lowering in the degree of cleanness of the clean room more effectively.
For achieving the above-mentioned object, in a first aspect of the present invention there is provided a work conveying system comprising a least a work holding means for holding a work and a horizontal moving means for moving the work holding means horizontally in an upper ceiling space within a clean room, the work being conveyed to each of plural processing apparatuses while circulating among the processing apparatuses, wherein the horizontal moving means has at least one linear moving mechanism, the linear moving mechanism comprising a traveling path covered with a duct and having a guide portion in the interior thereof, a traveling body adapted to engage the guide portion and travel through an interior space of the traveling path, and a slider connected to the traveling body and adapted to travel together with the traveling body in the exterior of the traveling path, the work holding means or another linear moving mechanism being attached to the slider, and cleaning means are disposed at suitable intervals in the traveling path to clean the air present within the traveling path and discharge the cleaned air to the exterior.
Since the invention in the first aspect is constructed as above, there can be obtained the following effects.
Since the traveling body, which is one constituent of the linear moving mechanism provided in the horizontal moving means, is adapted to engage the guide portion located within the traveling path covered with a duct and travel through the interior space of the traveling path, dust generated from a slide portion in which the traveling body and the guide portion are engaged with each other is confined into the duct and the possibility of its leaking out into the exterior clean room is decreased. Besides, since cleaning means for cleaning air present within the traveling path and discharging it to the exterior are disposed at suitable intervals in the traveling path, dust present in the traveling path is sucked and cleaned in the unit of a relatively short traveling path and the cleaned air is discharged to the exterior. Thus, it is possible to greatly decrease the proportion of dust leaking out into the clean room. Consequently, it becomes possible to keep high the degree of cleanness in the clean room.
In a second aspect of the present invention there is provided, in combination with the above first aspect, a work conveying system wherein a drive source, a drive mechanism, and a power supply means, which are for the traveling body, are accommodated in the interior of the traveling path, at least the drive source being integral with the traveling body.
According to this construction, the drive portion (including the drive source and the drive mechanism) is also positioned in the interior of the traveling path, whereby the possibility that the dust generated from the drive portion may leak out into the clean room located outside the duct is decreased. As a result, it becomes possible to keep higher the degree of cleanness in the clean room.
In a third aspect of the present invention there is provided, in combination with the above first or second aspect, a work conveying system wherein a base member serving as a base of a guide member having the guide portion constitutes a part of the duct, the guide member and the base member being formed by integral molding of the same material.
According to this construction, the guide member and the base member which constitutes a part of the duct can be fabricated at a low cost by drawing aluminum for example.
Further, in a fourth aspect of the present invention there is provided, in combination with any of the above first to third aspects, a work conveying system wherein in the horizontal moving means a plurality of the linear moving mechanisms are used in combination to permit the horizontal moving means to move arbitrarily in a horizontal plane in the upper ceiling space within the clean room.
According to this construction, the work conveying system can be constructed such that in the upper ceiling space within the clean room, fixed guide rails each provided with an individual linear moving mechanism are disposed horizontally in parallel on both sides, a traveling guide rail provided with an individual linear moving mechanism is laid between the fixed guide rails so that it can travel along both fixed guide rails, and a traveling block adapted to travel while holding the work is attached to the linear moving mechanism provided in the traveling guide rail so that the traveling block can travel along the traveling guide rail. Thus, a horizontal moving means capable of moving arbitrarily in a horizontal plane in the ceiling space can be constructed in a simple manner.
In a fifth aspect of the present invention there is provided, in combination with any of the above first to fourth aspects, a work conveying system wherein the work holding means is attached to the slider through a vertical moving means for moving the work holding means vertically.
According to this construction, a work conveying system provided with a three-dimensional moving means which permits arbitrary movement of the work holding means in a space within the clean room can be constructed in an extremely simple manner.
In a sixth aspect of the present invention there is provided a work conveying system comprising at least a work holding means for holding a work and a horizontal moving means for moving the work holding means horizontally in an upper ceiling space within a clean room, the work being conveyed to each of plural processing apparatuses while circulating among the processing apparatuses, wherein the horizontal moving means has at least one linear moving mechanism, the linear moving mechanism comprising a traveling path covered with a duct and having a guide portion in the interior thereof, a traveling body adapted to engage the guide portion and travel through an interior space of the traveling path, and a slider connected to the traveling body and adapted to travel together with the traveling body in the exterior of the traveling path, the work holding means or another linear moving mechanism being attached to the slider, and a deformable sealing means is provided in an elongated gap portion in which a connecting member for connecting the slider to the traveling body extends through the duct and travels along the traveling path, the sealing means covering the elongated gap portion without obstructing the travel of the connecting member.
In the sixth aspect constructed as above there can be obtained the following effects.
Since the traveling body as one constituent of the linear moving mechanism provided in the horizontal moving means of the work conveying system is adapted to engage the guide portion located within the traveling path covered with the duct and travel through the interior space of the traveling path, dust generated from a slide portion in which the traveling body and the guide portion are engaged with each other is confined into the duct and the possibility of its leaking out into the exterior clean room is decreased. Besides, since a deformable sealing means is provided in an elongated gap portion in which the connecting member for connecting the slider to the traveling body extends through the duct which covers the traveling path, the sealing means covering the elongated gap portion without obstructing the travel of the connecting member, the proportion of dust leaking out from the elongated gap portion into the clean room can be greatly decreased. Consequently, it becomes possible to keep high the degree of cleanness in the clean room.
Further, in a seventh aspect of the present invention there is provided a traveling path sealing structure in a work conveying system, the work conveying system including at least one linear moving mechanism, the linear moving mechanism comprising a traveling path covered with a duct and having a guide portion in the interior thereof, a traveling body adapted to engage the guide portion and travel through an interior space of the traveling path, and a slider connected to the traveling body and adapted to travel together with the traveling body in the exterior of the traveling path, the working holding means or another linear moving mechanism being attached to the slider, wherein a deformable sealing means is provided in an elongated gap portion in which a connecting member for connecting the slider to the traveling body extends through the duct and travels along the traveling path, the sealing means covering the elongated gap portion without obstructing the travel of the connecting member.
According to this construction there can be obtained the following effects.
Since the traveling body as one constituent of the linear moving mechanism provided in the work conveying system is adapted to engage the guide portion located in the interior of the traveling path covered with the duct and travel through the interior space of the traveling path, dust generated from a slide portion where the traveling body and the guide portion engage each other is confined into the duct and the possibility of its leaking out into the exterior clean room is decreased. Besides, since a deformable sealing member is provided in an elongated gap portion in which the connecting member for connecting the slider to the traveling body extends through the duct which covers the traveling path, the sealing means covering the elongated gap portion without obstructing the travel of the connecting member, it is possible to greatly decrease the proportion of dust leaking out to the exterior from the elongated gap portion. Consequently, the degree of cleanness of the external environment can be kept high.
In an eighth aspect of the present invention there is provided, in combination with the above seventh aspect, a traveling path sealing structure in a work conveying system wherein the sealing means is an expansion member in the shape of bellows which normally extends naturally to seal the elongated gap portion.
According to this construction, by merely providing in the elongated gap portion a bellows-like expansion member which is commonly used as a sealing member or a protective cover member, there can be easily obtained a deformable sealing means which covers the elongated gap portion without obstructing the travel of the connecting member.
In a ninth aspect of the present invention there is provided, in combination with the above seventh aspect, a traveling path sealing structure in a work conveying system wherein the sealing member is an expansion member which normally extends by virtue of magnetism to seal the elongated gap portion.
According to this construction, by magnetizing a lower edge of a commonly-used expansion member which lower edge extends along the elongated gap and by attracting the lower edge magnetically, the expansion member is extended to cover the elongated gap portion. Consequently, in a portion where the connecting member does not pass, the sealing of the elongated gap portion is ensured, with no obstruction to a smooth travel of the connecting member.
Further, in a tenth aspect of the present invention there is provided, in combination with the above eighth or ninth aspect, a traveling path sealing structure in a work conveying system wherein when looking in the traveling direction of the connecting member, in front of the connecting member are provided a first seal holding member for holding the sealing means in an initially closed state and a first seal opening member for subsequently opening the sealing member while the connecting member travels through the elongated gap portion, and at the rear of the connecting member are provided a second seal opening member for holding the sealing means in an initially opened state and a second seal holding member for subsequently closing the sealing member while the connecting member travels through the elongated gap portion.
According to this construction, closure of the elongated gap portion by the sealing means in a portion where the connecting member does not pass and release (opening) of the closure of the elongated gap portion by the sealing means in a portion where the connecting member passes are performed forcibly, so that both positive sealing of the elongated gap portion and smooth travel of the connecting member can be effected simultaneously.
In an eleventh aspect of the present invention there is provided, in combination with the above seventh aspect, a traveling path sealing structure in a work conveying system wherein the sealing means is constituted by a chain and normally hangs down naturally to seal the elongated gap portion.
According to this construction, by merely providing a chain as a commonly-used part in the elongated gap portion, it is possible to easily obtain a deformable sealing means which covers the elongated gap portion without obstructing the travel of the connecting member.
In a twelfth aspect of the present invention there is provided, in combination with the above seventh aspect, a traveling path sealing structure in a work conveying system wherein the sealing means comprises a pair of upper and lower elastic tubular members which press the connecting member constantly from above and below, and when the connecting member travels through the elongated gap portion, the connecting member travels while pushing aside the pair of upper and lower elastic tubular members vertically, while after passage of the connecting member, the pair of upper and lower elastic tubular members can immediately revert to their original shape.
According to this construction, by only providing the elongated gap portion with a pair of upper and lower elastic tubular members as commonly-used components, e.g., elastic tubular members (tubes or the like) having a bellows shape or a balloon shape in section, there can be easily obtained a deformable sealing means which covers the elongated gap portion without obstructing the travel of the connecting member.